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	$235.91	5.521%	$248.9346	$248.93	$248.95	$248.90
Purchase #2	$10.33	3.731%	$10.7154	$10.72	$10.70	$10.70
Purchase #3	$101.88	3.862%	$105.8146	$105.81	$105.80	$105.80
Purchase #4	$27.56	13.343%	$31.2373	$31.24	$31.25	$31.20
Purchase #5	$242.35	6.644%	$258.4517	$258.45	$258.45	$258.50
Purchase #6	$188.68	12.553%	$212.365	$212.37	$212.35	$212.40
Purchase #7	$156.46	7.285%	$167.8581	$167.86	$167.85	$167.90
7 purchase totals =	$963.17		$1,035.3767	$1,035.38	$1,035.35	$1,035.40