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	$132.60	12.320%	$148.9363	$148.94	$148.95	$148.90
Purchase #2	$93.45	7.282%	$100.255	$100.26	$100.25	$100.30
Purchase #3	$179.27	3.290%	$185.168	$185.17	$185.15	$185.20
Purchase #4	$242.40	13.813%	$275.8827	$275.88	$275.90	$275.90
Purchase #5	$178.37	8.611%	$193.7294	$193.73	$193.75	$193.70
Purchase #6	$179.50	10.678%	$198.667	$198.67	$198.65	$198.70
Purchase #7	$56.69	13.404%	$64.2887	$64.29	$64.30	$64.30
7 purchase totals =	$1,062.28		$1,166.9271	$1,166.94	$1,166.95	$1,167.00