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	$190.52	4.392%	$198.8876	$198.89	$198.90	$198.90
Purchase #2	$184.56	5.157%	$194.0778	$194.08	$194.10	$194.10
Purchase #3	$67.91	6.469%	$72.3031	$72.30	$72.30	$72.30
Purchase #4	$101.59	6.613%	$108.3081	$108.31	$108.30	$108.30
Purchase #5	$53.58	5.107%	$56.3163	$56.32	$56.30	$56.30
Purchase #6	$86.76	3.138%	$89.4825	$89.48	$89.50	$89.50
Purchase #7	$210.83	11.177%	$234.3945	$234.39	$234.40	$234.40
7 purchase totals =	$895.75		$953.7699	$953.77	$953.80	$953.80