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	$65.57	10.608%	$72.5257	$72.53	$72.55	$72.50
Purchase #2	$198.35	11.516%	$221.192	$221.19	$221.20	$221.20
Purchase #3	$95.56	11.561%	$106.6077	$106.61	$106.60	$106.60
Purchase #4	$74.88	10.815%	$82.9783	$82.98	$83.00	$83.00
Purchase #5	$28.70	13.857%	$32.677	$32.68	$32.70	$32.70
Purchase #6	$189.63	10.843%	$210.1916	$210.19	$210.20	$210.20
Purchase #7	$199.79	11.175%	$222.1165	$222.12	$222.10	$222.10
7 purchase totals =	$852.48		$948.2888	$948.30	$948.35	$948.30