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	$111.94	12.524%	$125.9594	$125.96	$125.95	$126.00
Purchase #2	$209.55	5.623%	$221.333	$221.33	$221.35	$221.30
Purchase #3	$82.96	9.796%	$91.0868	$91.09	$91.10	$91.10
Purchase #4	$140.96	9.556%	$154.4301	$154.43	$154.45	$154.40
Purchase #5	$56.76	5.195%	$59.7087	$59.71	$59.70	$59.70
Purchase #6	$210.69	8.640%	$228.8936	$228.89	$228.90	$228.90
Purchase #7	$134.96	5.459%	$142.3275	$142.33	$142.35	$142.30
7 purchase totals =	$947.82		$1,023.7391	$1,023.74	$1,023.80	$1,023.70