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	$207.63	4.474%	$216.9194	$216.92	$216.90	$216.90
Purchase #2	$98.89	5.758%	$104.5841	$104.58	$104.60	$104.60
Purchase #3	$235.76	3.308%	$243.5589	$243.56	$243.55	$243.60
Purchase #4	$10.27	9.729%	$11.2692	$11.27	$11.25	$11.30
Purchase #5	$130.82	8.240%	$141.5996	$141.60	$141.60	$141.60
Purchase #6	$187.91	11.221%	$208.9954	$209.00	$209.00	$209.00
Purchase #7	$112.70	6.743%	$120.2994	$120.30	$120.30	$120.30
7 purchase totals =	$983.98		$1,047.2260	$1,047.23	$1,047.20	$1,047.30