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	$85.52	11.147%	$95.0529	$95.05	$95.05	$95.10
Purchase #2	$150.66	3.767%	$156.3354	$156.34	$156.35	$156.30
Purchase #3	$221.82	6.765%	$236.8261	$236.83	$236.85	$236.80
Purchase #4	$152.33	9.487%	$166.7815	$166.78	$166.80	$166.80
Purchase #5	$181.95	7.104%	$194.8757	$194.88	$194.90	$194.90
Purchase #6	$196.31	13.374%	$222.5645	$222.56	$222.55	$222.60
Purchase #7	$106.31	13.743%	$120.9202	$120.92	$120.90	$120.90
7 purchase totals =	$1,094.90		$1,193.3563	$1,193.36	$1,193.40	$1,193.40