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	$196.97	7.689%	$212.115	$212.12	$212.10	$212.10
Purchase #2	$62.83	13.499%	$71.3114	$71.31	$71.30	$71.30
Purchase #3	$164.84	9.107%	$179.852	$179.85	$179.85	$179.90
Purchase #4	$185.93	13.414%	$210.8707	$210.87	$210.85	$210.90
Purchase #5	$67.74	7.185%	$72.6071	$72.61	$72.60	$72.60
Purchase #6	$54.95	13.506%	$62.3715	$62.37	$62.35	$62.40
Purchase #7	$81.31	6.662%	$86.7269	$86.73	$86.75	$86.70
7 purchase totals =	$814.57		$895.8546	$895.86	$895.80	$895.90