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	$113.92	11.707%	$127.2566	$127.26	$127.25	$127.30
Purchase #2	$71.75	12.444%	$80.6786	$80.68	$80.70	$80.70
Purchase #3	$82.89	10.498%	$91.5918	$91.59	$91.60	$91.60
Purchase #4	$181.29	11.357%	$201.8791	$201.88	$201.90	$201.90
Purchase #5	$197.55	13.332%	$223.8874	$223.89	$223.90	$223.90
Purchase #6	$212.74	9.866%	$233.7289	$233.73	$233.75	$233.70
Purchase #7	$194.69	12.476%	$218.9795	$218.98	$219.00	$219.00
7 purchase totals =	$1,054.83		$1,178.0019	$1,178.01	$1,178.10	$1,178.10