Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$119.74	6.852%	$127.9446	$127.94	$127.95	$127.90
Purchase #2	$142.40	3.515%	$147.4054	$147.41	$147.40	$147.40
Purchase #3	$152.60	13.225%	$172.7814	$172.78	$172.80	$172.80
Purchase #4	$92.50	10.161%	$101.8989	$101.90	$101.90	$101.90
Purchase #5	$147.26	3.592%	$152.5496	$152.55	$152.55	$152.50
Purchase #6	$156.95	10.298%	$173.1127	$173.11	$173.10	$173.10
Purchase #7	$128.46	10.235%	$141.6079	$141.61	$141.60	$141.60
7 purchase totals =	$939.91		$1,017.3005	$1,017.30	$1,017.30	$1,017.20