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	$195.95	11.304%	$218.1002	$218.10	$218.10	$218.10
Purchase #2	$202.31	10.323%	$223.1945	$223.19	$223.20	$223.20
Purchase #3	$67.55	9.466%	$73.9443	$73.94	$73.95	$73.90
Purchase #4	$195.45	5.320%	$205.8479	$205.85	$205.85	$205.80
Purchase #5	$18.29	9.355%	$20.001	$20.00	$20.00	$20.00
Purchase #6	$92.34	6.199%	$98.0642	$98.06	$98.05	$98.10
Purchase #7	$201.27	10.510%	$222.4235	$222.42	$222.40	$222.40
7 purchase totals =	$973.16		$1,061.5756	$1,061.56	$1,061.55	$1,061.50