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	$152.56	9.544%	$167.1203	$167.12	$167.10	$167.10
Purchase #2	$147.41	8.830%	$160.4263	$160.43	$160.45	$160.40
Purchase #3	$211.73	5.273%	$222.8945	$222.89	$222.90	$222.90
Purchase #4	$82.82	13.696%	$94.163	$94.16	$94.15	$94.20
Purchase #5	$205.62	9.198%	$224.5329	$224.53	$224.55	$224.50
Purchase #6	$232.74	4.560%	$243.3529	$243.35	$243.35	$243.40
Purchase #7	$30.32	13.446%	$34.3968	$34.40	$34.40	$34.40
7 purchase totals =	$1,063.20		$1,146.8867	$1,146.88	$1,146.90	$1,146.90