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	$188.65	11.383%	$210.124	$210.12	$210.10	$210.10
Purchase #2	$6.83	3.783%	$7.0884	$7.09	$7.10	$7.10
Purchase #3	$76.57	12.227%	$85.9322	$85.93	$85.95	$85.90
Purchase #4	$245.72	13.118%	$277.9535	$277.95	$277.95	$278.00
Purchase #5	$180.95	3.794%	$187.8152	$187.82	$187.80	$187.80
Purchase #6	$140.48	8.366%	$152.2326	$152.23	$152.25	$152.20
Purchase #7	$174.47	9.426%	$190.9155	$190.92	$190.90	$190.90
7 purchase totals =	$1,013.67		$1,112.0614	$1,112.06	$1,112.05	$1,112.00