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	$91.91	3.864%	$95.4614	$95.46	$95.45	$95.50
Purchase #2	$73.38	5.540%	$77.4453	$77.45	$77.45	$77.40
Purchase #3	$90.81	10.327%	$100.1879	$100.19	$100.20	$100.20
Purchase #4	$188.56	3.148%	$194.4959	$194.50	$194.50	$194.50
Purchase #5	$197.41	12.467%	$222.0211	$222.02	$222.00	$222.00
Purchase #6	$245.26	12.298%	$275.4221	$275.42	$275.40	$275.40
Purchase #7	$53.98	10.262%	$59.5194	$59.52	$59.50	$59.50
7 purchase totals =	$941.31		$1,024.5531	$1,024.56	$1,024.50	$1,024.50