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	$181.99	5.478%	$191.9594	$191.96	$191.95	$192.00
Purchase #2	$148.43	9.165%	$162.0336	$162.03	$162.05	$162.00
Purchase #3	$67.96	5.148%	$71.4586	$71.46	$71.45	$71.50
Purchase #4	$77.71	6.125%	$82.4697	$82.47	$82.45	$82.50
Purchase #5	$193.93	11.397%	$216.0322	$216.03	$216.05	$216.00
Purchase #6	$94.74	10.764%	$104.9378	$104.94	$104.95	$104.90
Purchase #7	$167.85	12.580%	$188.9655	$188.97	$188.95	$189.00
7 purchase totals =	$932.61		$1,017.8568	$1,017.86	$1,017.85	$1,017.90